Hello,

Roy Marples, le ven. 12 juin 2026 07:54:23 +0100, a ecrit:
>  > One can set async mode only around the mach_msg call for instance. 
> 
> That would be an option as well, but the more I learned about pthreads for 
> the I lean
> towards marking critical sections of my code as non cancellable.

Yes, to make the code simpler you can also enable cancellation only at
the blocking spot.

>  > > The big benefit for me NOT using libpcap for this is that I discovered 
> that dhcpcd's 
>  > > ARP BPF code is too big to fit in the Mach kernel. 
>  >  
>  > The Mach kernel? The network drivers rather live in netdde, and the bpf 
>  > support comes from libbpf inside the hurd repository. If there is a 
>  > limitation there it can very probably be lifted. 
> 
> https://cgit.git.savannah.gnu.org/cgit/hurd/gnumach.git/tree/include/device/bpf.h#n195
> https://cgit.git.savannah.gnu.org/cgit/hurd/gnumach.git/tree/include/device/net_status.h#n80
> 
> That is the limitaton I'm talking about.

Again, this is the kernel code, the actual bpf support is in libbpf
inside the hurd. But the limitation is indeed the same.

> Here's the equivalent limit in NetBSD
> https://nxr.netbsd.org/xref/src/sys/net/bpf.h#67

Ok, I have raised it to 512 in libbpf.

Samuel

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